在本論文中，我們使用低能量電子繞射(LEED)與角解析光電子能譜(ARPES)來研究雙層鍺烯(Bilayer Germanene)的成長，並使用鉛原子來幫助銀(111)基板上的雙層鍺烯形成，透過程式模擬LEED圖以及計算HOC(Higher-Order Coincidence)，來分析雙層鍺烯的結構。
　　首先，我們將鍺沉積到銀(111)基板上，隨著鍺的量增加，結構會從最初的Ag2Ge合金相轉變為條紋相SP(Striped phase)，隨後轉變為準獨立相QP(Quasi-freestanding phase)。然後我們將鉛原子沉積到QP上，在頂部形成單層鉛，其晶格結構為(√(175/124)×√(175/124))R10.16°±1。接下來我們逐步沉積鍺原子，然後退火以重新排列鉛與鍺原子。我們發現所有的鉛原子都移動到銀(111)表面並形成(√(28/19)×√(28/19))R±4.3°的結構，並擠壓QP與之並排共存。隨著鍺的鍍量來到2 ML，新的LEED訊號出現，表明雙層鍺烯的形成。根據我們的分析，雙層鍺烯有兩組晶格常數為 3.50 Å 和 4.04 Å，對應於我們觀察到的雙層鍺烯的頂部第一層和更深層的晶格結構。而AB堆疊模型的可能性更大。 ARPES 測量揭示了與基於雙層鍺烯的 AB 堆疊模型的第一性原理計算相似的帶特徵。

In this thesis, we used low-energy electron diffraction (LEED) and angle-resolved photoemission spectroscopy (ARPES) to study the growth of bilayer germanene.
We used Pb atoms to help the formation of bilayer germanene on Ag(111) and analyzed the structure of bilayer germanene by simulating the LEED patterns and calculating HOC(Higher-Order Coincidence).
First, we deposited Ge onto the Ag (111) substrate. As the amount of Ge increases, an initial Ag2Ge alloy phase transited to striped-phase (SP) germanene and subsequently evolved to quasi-freestanding phase (QP). We then deposited Pb atoms onto QP to form a monatomic Pb layer on top with the lattice structure √(175/124)×√(175/124))R10.16°±1°.Next we deposited Ge step by step, followed by annealing to rearrange the Pb and Ge atoms. We discovered that all the Pb atoms moved to Ag(111) surface forming (√(28/19)×√(28/19))R±4.3° structure to squeeze with QP germanene side by side. As the Ge amount increases to 2 ML, new LEED spots emerge indicating the formation of bilayer germanene. According to our analysis, there are two lattice constants of 3.50 Å and 4.04 Å, corresponding to lattice structures of the top first layer and deeper layers of the bilayer germanene we observed. And AB stacking model is more likely. ARPES measurement reveals the band features resembling those from the first-principles calculation based on the AB stacking model of bilayer germanene.

摘要 i
Abstract ii
目錄 iii
第一章　緒論 1
第二章　基本理論 2
2.1 晶體結構 2
2.1.1倒晶格 4
2.1.2勞厄條件 5
2.1.3布里淵區 5
2.1.4 蜂窩狀結構(Honeycomb structure) 6
2.2表面 8
2.2.1表面重構(surface reconstruction) 9
2.2.2 Wood's notation 9
2.2.3 Monolayer 10
2.3 Find Higher-Order Coincidence 10
2.4 低能量電子繞射儀(Low-energy electron diffraction) 12
2.4.1 LEED 單次散射(Single scattering) 12
2.4.2 考慮旋轉下的單次散射成像條件 16
2.4.3 LEED 二次散射(Double scattering) 18
2.4.4非彈性平均自由徑(Inelastic mean free path) 20
2.5 光電子能譜(Photoemission Spectroscopy) 21
2.5.1 光電效應(Photoelectric effect) 21
2.5.2 角解析光電子能譜(ARPES) 22
第三章 實驗儀器與原理 24
3.1 超高真空系統與幫浦 24
3.1.1 幫浦與原理介紹 24
3.1.1.1 乾式渦卷幫浦(Dry Scroll Pump) 25
3.1.1.2 渦輪分子幫浦(Turbo Molecular Pump) 26
3.1.1.3 離子幫浦(ion pump) 27
3.1.1.4 鈦昇華幫浦(Titanium Sublimation Pump) 28
3.2 離子濺射槍(Sputter gun) 29
3.3 殘留氣體分析儀(Residual Gas Analysis) 29
3.4 蒸鍍槍(Knudsen evaporator cell) 31

3.5 低能量電子繞射儀(Low-Energy Electron Diffraction) 32
3.6光源 34
3.6.1 氦氣燈(Helium lamp) 34
3.6.2 同步輻射光 35
3.7 能量分析儀(Energy analyzer) 35
第四章 實驗結果與討論 37
4.1 文獻回顧與實驗動機 37
4.1.1鍺成長在銀(111)上的三種結構 37
4.1.2雙層鍺烯(Bilayer germanene)結構 38
4.1.3實驗動機 40
4.2 雙層鍺烯製備與結構分析 41
4.2.1 樣品製備流程 41
4.2.2 銀(111)單晶 41
4.2.3 第一階段在銀(111)單晶上鍍鍺 42
4.2.4 第二階段鍍鉛 44
4.2.4.1 鍍鉛0.25ML 44
4.2.4.2 鍍鉛0.25 ML~1 ML之過程 45
4.2.4.3 鍍鉛1 ML 47
4.2.5 第三階段鍍鍺並退火 48
4.2.5.1 鍍鍺0.4 ML並退火 48
4.2.5.2 鍍鍺0.4 ML~2 ML之過程 50
4.2.5.3 鍍鍺2 ML 並退火 52
4.2.5.4 雙層鍺烯(Bilayer Germanene)之原子結構圖 54
4.3 計算Higher-order coincidence 55
4.3.1 雙層鍺烯結構成長 55
4.3.2 Higher-order coincidence(HOC) 56
4.4 ARPES 58
第五章 結論 59
參考文獻 60

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